Department of Chemical and Biological Engineering, University of British Columbia, Vancouver, Canada.
Department of Civil, Geological and Mining Engineering, Polytechnique Montreal, Quebec, Canada.
Environ Pollut. 2019 Oct;253:790-799. doi: 10.1016/j.envpol.2019.07.062. Epub 2019 Jul 12.
Microcystin-LR (MCLR) is the most commonly encountered toxic microcystin variant. MCLR is usually present along with common surface water constituents such as inorganic ions and natural organic matter (NOM) which compete with MCLR for active sites during ion exchange (IX) process. Consequently, development of a multicomponent competitive model is essential for practical IX applications. This is critically important given that the NOM characteristics (charge density and molecular weight distribution) and inorganic ions concentrations are spatially variable and can change seasonally. In the present study, a systematic study was carried out into the multicomponent interactions of IX resin with inorganic ions and NOM during the MCLR removal process. This involved evaluation of MCLR removal in a single component system (i.e., MCLR only), a dual component system (MCLR and one other contaminant such as NOM), and a multiple component system (MCLR with NOM and different inorganic ions present in natural waters). A comprehensive understanding of the dynamic adsorption behavior showed that the experimental data for single component systems agree well with a Freundlich isotherm. For multicomponent interactions, the Equivalent Background Concentration (EBC) model which is derived from the Ideal Adsorption Solution Theory (IAST) provided the best correlation with the experimental data in natural waters. The concentrations of competing NOM and inorganic ions estimated by the EBC model were <10% of their initial concentrations. Sulphates are the most competitive inorganic ions followed by nitrates and bicarbonates and the multicomponent interactions could be well predicted by using the IAST-EBC model. However, the EBC model failed in the presence of higher molecular weight Suwannee River Humic Acid (SRHA) molecules due to neglecting of the pore blocking phenomenon. In the presence of higher molecular weight SRHA molecules, the Redlich-Peterson Isotherm (RP) model exhibited a better performance than the Sheindorf-Rebuhn-Sheintuch (SRS) and the EBC models.
微囊藻毒素-LR (MCLR) 是最常见的有毒微囊藻变异体。MCLR 通常与常见的地表水成分（如无机离子和天然有机物 (NOM)）共存，这些成分在离子交换 (IX) 过程中会与 MCLR 竞争活性位点。因此，开发多组分竞争模型对于实际的 IX 应用至关重要。鉴于 NOM 特性（电荷密度和分子量分布）和无机离子浓度在空间上是可变的，并且可能会随季节变化，这一点非常重要。在本研究中，系统研究了 IX 树脂在 MCLR 去除过程中与无机离子和 NOM 的多组分相互作用。这包括评估单一组分系统（即仅 MCLR）、双组分系统（MCLR 和其他一种污染物，如 NOM）和多组分系统（存在天然水中的 NOM 和不同无机离子的 MCLR）中的 MCLR 去除情况。对动态吸附行为的全面了解表明，单一组分系统的实验数据与 Freundlich 等温线吻合良好。对于多组分相互作用，源自理想吸附溶液理论 (IAST) 的等效背景浓度 (EBC) 模型与天然水中的实验数据具有最佳相关性。EBC 模型估计的竞争 NOM 和无机离子浓度<其初始浓度的 10%。硫酸盐是最具竞争力的无机离子，其次是硝酸盐和碳酸氢盐，多组分相互作用可以通过使用 IAST-EBC 模型很好地预测。然而，由于忽略了孔阻塞现象，EBC 模型在存在高分子量苏湾河腐殖酸 (SRHA) 分子时会失效。在存在高分子量 SRHA 分子的情况下，Redlich-Peterson 等温线 (RP) 模型的表现优于 Sheindorf-Rebuhn-Sheintuch (SRS) 和 EBC 模型。
